The Enzyme Linked ImmunoSorbent Assay, or ELISA, is a test used for detecting and quantifying antibodies or antigens. This technique is used in immunology, microbiology, endocrinology, and other fields, as well as in the food industry. The ELISA can measure the concentration of antibodies or antigens (generally referred to as analyte) in a solution by the observation of a color change.
Generally, an antigen is any molecule that induces the production of antibodies when introduced into an organism. For example, any foreign particle such as portions of bacteria, viruses, pollen, and other such molecules as well as self-antigens can be identified by an organism as antigens. In addition, antibodies are proteins produced by the immune system in response to antigen detection.
The ELISA process involves a coating or binding of an antigen, antibody, or other molecule to a solid support as a membrane or a 96-well micro plate or microtiter plate, also referred to as an ELISA plate. An enzyme conjugate is used to detect the binding of an antigen or an antibody to solid phase attached molecule. The enzyme converts a colorless substrate (chromogen) to a colored product, thereby indicating the presence of antigen: antibody binding. Thus, the ELISA test can be used to detect either the presence of antigens or antibodies in a sample depending on how the system is set up.
To run an ELISA test—by hand or automated instruments—plate washer instruments, plate reader instruments, and fully automated ELISA instruments are globally manufactured and distributed worldwide. According to the International Organization for Standardization's standard providing general requirements for the competence of testing in medical laboratories, including ISO 15189, as well as national standards across many countries. Validation of instrument quality is crucial. Thus, quality control processes for such quality validation are also important and necessary for components such as plate washer instruments, plate reader instruments, and fully automated ELISA instruments.
The lack of a comprehensive tool to assess the quality control parameters of fully automated ELISA instruments has resulted in the reliance of diagnostic clinical laboratories solely on commercial serum controls that are available in the market in order to assess the experimental results of such instruments. However, these commercial serum controls are associated with many drawbacks. For example, it is known that use of the serum controls permit only the assessment of quality parameters such as precision and accuracy, while other important quality parameters involved in the use of a fully automated EISA instrument cannot be evaluated. Furthermore, when errors arise in the results obtained from commercial serum controls, there is no debugging mechanism to indicate that the problem stems from the ELISA kit that is being used rather than from the fully automated ELISA instrument. In addition, commercial serum controls are not available for all target analytes. As each commercial control serum contains a limited category of target analytes, to assess the quality of all the target analytes tests, a number of commercial serum control must be used. Furthermore, due to a broad range of acceptable results suggested by commercial serum control manufacturers, the underlying problems in an instrument may not be immediately captured, especially during the initial instrument setup. These commercial serum controls are also expensive and extended use of these materials is not cost-effective.
Thus, as various processes and techniques across a wide variety of medical and diagnostic clinical fields have become increasingly automated, the need for an efficient and effective means of providing reliable quality control for such systems has become increasingly paramount. Currently, there are some protocols and kits available to assess the quality of plate washer instruments and plate reader instruments used in manually operated ELISA tests. However, there remains a need for protocols, kits, and/or equipment to assess the quality of fully automated ELISA instruments.